1. Field of the Invention
The present invention relates to apparatuses using a battery, such as electronic still cameras or digital video cameras.
2. Description of the Related Art
A typical image capture apparatus, such as an electronic still camera or a digital video camera, includes an apparatus body that records and reproduces image data on an object, and a battery pack that is connected to the apparatus body so as to supply power thereto. The battery pack is removably mounted on the apparatus body, and can be charged with current from an external AC power adaptor.
When the battery pack is mounted on the apparatus body, an available time for which the image capture apparatus can be used by the use of the battery pack is calculated, and is displayed in a display unit of the apparatus body (for example, see Japanese Patent Laid-Open No. 2007-20203). This improves convenience, because the user can recognize how many hours (minutes) for which the user can use the apparatus for image capture and playback, in particular, when carrying the apparatus.
In some image capture apparatuses of this type, a voltage Vo and a voltage Vs are required. The end of the available time is displayed (e.g., 0 minute is displayed) when a battery voltage of the battery pack reaches the voltage Vo, and a low power operation (e.g., shutdown) is carried out when the battery voltage of the battery pack reaches the voltage Vs. In this case, the voltage Vo is usually more than or equal to the voltage Vs (Vo≧Vs).
However, in a low-temperature state or a high-power discharging state, the voltage Vo sometimes becomes less than the voltage Vs. In this case, the low power operation is suddenly started although the display shows that several minutes are left as the available time.
In this way, the image capture apparatuses as the related art are sometimes used in the environment where the available time is not accurately indicated to the user. This problem also may occur in apparatuses other than the image capture apparatuses.